1. Field of the Invention
The present invention relates to a packet switch, and more particularly to an improved system in the connection between a speech path equipment and a control equipment in the packet switch and the transmission of a control signal.
2. Description of the Related Art
As described in "Digital Switch for Telephone" DIGITAL COMMUNICATION SERIES, published by Sangyo Tosho Co , Ltd., 1986 (p. 117), a conventional digital switch comprises a speech path for accommodating a transmission line and exchanging packets and a controller for controlling various equipments of the speech path such as, a distribution speech path equipment (hereinafter referred to as a switch), a concentrator and a subscriber circuit. The equipments of the speech path and the controller are connected through a speech path bus to allow the transmission and reception of control information between the speech path and the controller.
The digital switch thus constructed has the following problems.
As a connection distance of the speech path increases, noises are included and the reliability of the control signal transmitted and received between the speech path and the controller is lowered. Thus, there is a restriction in the separation and the increase of distance between the equipments of the speech path and the controller. Where the equipments are interconnected by the speech path bus, it is necessary, when a specification is modified such as the expansion of the speech path, to accommodate the transmission path into the added equipment as well as to connect a new speech path bus between the added equipment and the controller.